1. Field of the Invention
The present invention relates to a lamp-positioning device and the backlight module using the same; most specifically to a lamp-positioning device used in a backlight module of a liquid crystal display.
2. Description of the Prior Art
In recent years, liquid crystal displays has become the mainstream in various types of display devices. Liquid crystal displays are extensively used in electronic products such as home televisions, monitors of personal computers and laptop computers, display screens of mobile phones and digital cameras. In liquid crystal displays, the backlight modules are used to provide bright and evenly distributed light for the liquid crystal display to display desired images. The backlight modules include edge-lighting backlight module and bottom-lighting backlight module respectively suitable for liquid crystal displays of different sizes.
FIG. 1A and FIG. 1B illustrate a lamp-holding device 10 of a conventional backlight module. The lamp-holding device 10 includes a base 20, two arms 30 and a stand 50, wherein the stand 50 is connected to and extends from the base 20. Two arms 30 are both connected to the stand 50 and also bend respectively to form an arch. A plurality of protrusions 31 are formed on the inner surface of the arms 30 for contacting a lamp 40. In other words, a holding space 21 is formed between the protrusions 31. Afterward the lamp 40 passes through the opening between two arms 30 and is then positioned in the holding space 21 while making contacts with the protrusions 31.
The lamp 40 used in backlight module is vulnerable to vibration and shock which cause the lamp to crack or deviate. Thus the lamp 40 should be fixed to the lamp-holding device and operated with the optical films in order to provide bright and evenly distributed light. The tolerance in manufacturing the conventional lamp-holding devices, such as different in molds used, may create deviation in the sizes of conventional lamp-holding devices. In other words, sizes of the holding spaces 21 and sizes of the opening between two arms 30 may deviate.
If the holding space 21 is much smaller than the lamp, due to manufacturing tolerance. The lamp may be tightly grasped and thus may easily crack or break due to vibration or shock. Furthermore, the tightly grasped lamp may have inefficient heat dispersion because the lamp-holding device is held too close to the lamp; the resultant accumulation of heat may create dark spot in the lamp. On the other hand, if the size of holding space 21 is much greater than that of the lamp then excessive space may occur between the holding space and the lamp. Thus the lamp may move due to high frequency vibration within the backlight module which creates noises due to collision between the lamp and the lamp-holding device.
Furthermore, a lamp port is formed between two arms 30 and the tolerance in manufacturing of lamp-holding device may result in a lamp port whose diameter is much smaller than that of the lamp. Thus before the lamp is placed in the holding space, the lamp has to enter the lamp port by pushing the arms outward. In this way, the lamp may crack or cause the arms to deform due to excessive force during assembly. On the other hand, if the lamp port is enlarged due to tolerance in manufacturing, it will be difficult for the lamp-holding device to hold the lamp firmly. The lamp may be escape through the lamp port due to vibration and shock and thus causes damages to the lamp.
The above-mentioned situations can all create inconvenience in backlight module assembly and even damages to the element used in the backlight module. The above-mentioned situations can increase the assembly hours required and the associated production costs and can also reduce the life of lamp as well as the quality of overall products.